They are at the beginning because they absorb the energy from the sun and the energy or the sun gets transferred by each organisms
It allows the scientist to determine the effect of the changed variable , it also allows samples and organisms to be tested under comfortable conditions
Answer:
D
Explanation:
The first step in DNA replication is to 'unzip' the double helix structure of the DNA molecule. This is carried out by an enzyme, called helicase which breaks the hydrogen bonds? holding the complementary bases of DNA together